Biology Chapter 6: Chromosomes & Cell Division

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Questions and Answers

What is the difference between prokaryotic chromosomes and eukaryotic chromosomes?

Prokaryotic cells have a single circular chromosome attached to the cell membrane, while eukaryotic cells contain free-floating linear chromosomes within a nucleus.

Before a cell divides, what happens to the cell's chromosomes?

They are duplicated.

What happens to eukaryotic chromosomes with each cell division?

They are shortened.

How do telomeres partially solve the shortening problem?

Telomeres act as a buffer during cell division, allowing a critical number of divisions before functional DNA is lost. Signup and view all the answers

What is a telomere?

A section of non-coding repetitive DNA that serves as a protective cap at the tip of every chromosome. Signup and view all the answers

Teolmerase is?

An enzyme that adds DNA sequence repeats to the ends of telomeres. Signup and view all the answers

Describe Binary Fission in Prokaryotes.

<ol> <li>An exact copy of the cell's DNA is created; 2. The cell elongates and begins to pinch into two; 3. Two daughter cells are formed.</li> </ol> Signup and view all the answers

Are telomeres used in binary fission in prokaryotes?

False Signup and view all the answers

What are the 5 stages of the eukaryotic cell cycle and what occurs at each stage?

<ol> <li>Gap 1: Primary growth phase; 2. DNA Synthesis: Preparation for division; 3. Gap 2: Second growth phase; 4. Mitosis: Division of the nucleus; 5. Cytokinesis: Division of the cytoplasm.</li> </ol> Signup and view all the answers

Which of the stages of the eukaryotic cell cycle occur during interphase?

Gap 1, DNA Synthesis, Gap 2. Signup and view all the answers

Why must a cell's DNA be replicated for cell division to occur?

To ensure each daughter cell gets a full set of DNA identical to the parent cell. Signup and view all the answers

What enzymes are used in the DNA replication process?

Unwinding and Rebuilding enzymes. Signup and view all the answers

Explain unwinding and rebuilding as used in the DNA replication process. What is the result?

<ol> <li>Unwinding: DNA unwinds into two strands; 2. Rebuilding: Enzymes synthesize new strands complementary to the original strands.</li> </ol> Signup and view all the answers

Why is DNA replication a semi-conservative process?

Because half of each of the two new molecules comes from the original molecule. Signup and view all the answers

What are the characteristics of cancer?

No contact inhibition and continued division. Signup and view all the answers

What is metastasis?

The spread of cancer cells to other parts of the body. Signup and view all the answers

What is the difference between normal cells and cancer cells?

Normal cells stop dividing when they contact other cells, while cancer cells ignore these signals and continue to divide. Signup and view all the answers

Why are cancers dangerous?

They grow larger, pressing against neighboring cells and tissues, disrupting functions. Signup and view all the answers

Study Notes

Chromosomes in Prokaryotes vs. Eukaryotes

Prokaryotic chromosomes are single and circular, attached to the cell membrane.
Eukaryotic chromosomes are linear, free-floating, and contained within a nucleus.

Chromosome Duplication Before Division

Chromosomes are duplicated before cell division to ensure each daughter cell receives identical genetic material.

Eukaryotic Chromosome Shortening

With each division, eukaryotic chromosomes become shorter, impacting genetic information over time.

Telomeres and the Shortening Problem

Telomeres shorten with each division, providing a buffer against immediate loss of functional DNA.
Functional DNA loss occurs after approximately 50 divisions in humans, leading to cellular aging and death.

Definition of Telomeres

Telomeres are repetitive non-coding DNA sections that protect chromosome ends from degradation.

Role of Telomerase

Telomerase is an enzyme that extends telomeres, allowing for continued cell division and longevity in some cells.

Binary Fission in Prokaryotes

DNA is copied exactly, the cell elongates, and eventually splits into two daughter cells.

Telomeres in Binary Fission

Telomeres are not utilized in binary fission since prokaryotic chromosomes lack them.

Stages of the Eukaryotic Cell Cycle

Gap 1: Cell undergoes primary growth and normal functions like protein synthesis.
DNA Synthesis: Each chromosome replicates to prepare for division.
Gap 2: Further growth and preparation for mitosis.
Mitosis: Division of the parent cell's nucleus and duplicated chromosomes.
Cytokinesis: Division of the cytoplasm into two daughter cells, each receiving a complete set of DNA.

Interphase Stages

Interphase consists of Gap 1, DNA Synthesis, and Gap 2.

Importance of DNA Replication

DNA replication is essential for providing daughter cells with an identical genetic blueprint.

Enzymes in DNA Replication

Unwinding and rebuilding enzymes are critical in separating DNA strands and synthesizing new strands.

Unwinding and Rebuilding Process

DNA unwinds into two strands, and enzymes add nucleotides to form new complementary strands, resulting in two double-stranded molecules identical to the original.

Semi-Conservative DNA Replication

Each new DNA molecule contains one strand from the original and one newly synthesized strand.

Characteristics of Cancer

Cancer cells exhibit no contact inhibition and continue to divide uncontrollably.

Metastasis Explained

Cancer cells lack cohesion, allowing them to spread rapidly throughout the body, forming secondary tumors.

Normal vs. Cancer Cells

Normal cells stop dividing upon contact with other cells, while cancer cells ignore such signals and continue to proliferate.

Dangers of Cancer

Malignant tumors can grow large enough to disrupt surrounding tissues and organs, potentially leading to fatal outcomes.

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Description

Test your knowledge of chromosomes and the cell division process with these flashcards. Learn the key differences between prokaryotic and eukaryotic chromosomes, and understand what happens to chromosomes before cell division. Perfect for students studying biology at any level.